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The calculator converts your height in cm to inches, subtracts 60 to get the inches over 5 ft, and runs three classic equations. Devine (1974, built for drug dosing), Hamwi (1964, built for dietitians and diabetes nutrition plans), and Robinson (1983, fitted to observed population data) each start from a base weight at 5 ft and add a fixed amount per inch above it. The healthy range is 90% to 110% of the Devine result. These are estimates, not medical advice: the formulas ignore muscle mass, frame size, age, and health history, so use them as a reference point and talk to a qualified professional before acting on any weight target.
Ideal body weight (IBW) is a reference estimate of a healthy weight for your height and gender, derived from population averages. The three classic equations behind it were developed between 1964 and 1983 for clinical uses such as drug dosing, and they remain the standard quick reference today. This calculator runs the Devine, Hamwi, and Robinson formulas together, so instead of one rigid number you see a cluster of estimates plus a healthy weight range built from the Devine result. All results are estimates and guidance, not medical advice. Talk to a doctor or dietitian before setting a weight target or changing your diet.
All three formulas share one shape: a base weight for someone five feet tall, plus a fixed amount for each inch above 5 ft (60 inches). Height in inches is your height in cm divided by 2.54, and below 5 ft the per-inch term is floored at zero so you simply get the base weight.
Devine (1974): men 50 + 2.3 × inches over 5 ft; women 45.5 + 2.3 × inches over 5 ft. Published by B.J. Devine for ideal body weight in drug dosing, it is the most cited IBW formula in clinical practice.
Hamwi (1964): men 48 + 2.7 × inches over 5 ft; women 45.5 + 2.2 × inches over 5 ft. Developed by Dr. George Hamwi as a quick reference for dietitians and diabetes nutrition plans. It has the steepest per-inch increment.
Robinson (1983): men 52 + 1.9 × inches over 5 ft; women 49 + 1.7 × inches over 5 ft. A later refinement fitted to observed population data, with the gentlest slope of the three.
Take a man 175 cm tall and run every step by hand:
Convert to inches: 175 / 2.54 = 68.9 inches. Inches over 5 ft: 68.9 - 60 = 8.9. Devine: 50 + 2.3 × 8.9 = 70.5 kg. Hamwi: 48 + 2.7 × 8.9 = 72.0 kg. Robinson: 52 + 1.9 × 8.9 = 68.9 kg. Healthy range: 90% to 110% of the Devine result = 63.4 to 77.5 kg.
The three formulas cluster within about 3 kg of each other. That cluster, and the healthy range around it, is the practical target: far more useful than any single figure.
Hamwi usually gives the highest figure for tall people because of its steep 2.7 kg per inch increment; Robinson gives the lowest because its 1.9 and 1.7 kg increments are the gentlest. Devine sits between the two and remains the default reference for medication dosing, while Robinson is often preferred in modern medical references as a general reference point.
The practical difference is small: for a 175 cm man the spread is only about 3 kg, and every formula lands near the middle of the healthy BMI range for that height. None of the three includes age, muscle mass, or frame size, so treat the cluster as one opinion among several, not a verdict.
A quick 5'10 male check: 70 inches is 10 over 5 ft, so Devine gives 50 + 2.3 × 10 = 73.0 kg, Hamwi gives 48 + 2.7 × 10 = 75.0 kg, and Robinson gives 52 + 1.9 × 10 = 71.0 kg. Many sites publish an ideal weight by height table or an ideal weight chart by height; those are just these same formulas evaluated at round heights, not new science.
Ideal body weight formulas give single numbers from your height and gender, usually landing near the centre of the healthy BMI range. BMI gives a range instead: the WHO healthy band of 18.5 to 24.9, which for a 175 cm person spans roughly 56.7 to 76.3 kg. BMI is built for population screening; IBW was built as a quick reference originally for drug dosing.
Both share the same blind spot: neither can tell muscle from fat. A muscular athlete can be above every formula and outside the BMI band while carrying very low body fat. Body fat percentage is the measure that actually distinguishes composition.
Muscle mass: athletes, bodybuilders, and manual workers will look overweight by every formula. If you train with weights, body fat percentage is a better guide than any height-based number.
Frame size: a larger frame (wider wrists, broader shoulders) can shift a healthy weight roughly 10% above the formula result, so a frame size adjustment of plus or minus 10% is a common rough correction. The classic wrist test: wrap your thumb and middle finger around the opposite wrist. Overlapping means a small frame, just touching means medium, a gap means large. Frame size can affect where your personal healthy weight sits inside the range, even though it never changes the formula itself.
Age: the formulas ignore age, but older adults may be healthiest slightly above the mid-range because some reserve helps recovery from illness.
Pregnancy and childhood: IBW does not apply during pregnancy, and children are assessed with pediatric growth charts, not these formulas.
These results are estimates, not medical advice. They cannot account for body composition, ethnicity, health history, or individual circumstances, so discuss any weight target with a qualified healthcare professional.
Enter your height in centimetres (120 to 230) and select your gender. The calculator converts your height to inches, works out the inches over 5 ft, and instantly shows the Devine, Hamwi, and Robinson results side by side, plus the healthy range set at 90% to 110% of the Devine figure.
Read the cluster, not one number: knowing what you should weigh for your height is only the starting point. if your weight sits inside or near the healthy range and you are active with good energy and health markers, the exact kilogram matters less than the trend. Use the result as a starting point for a conversation with a doctor or dietitian, not as a target to chase on your own.
Enter your height in cm and select your gender. The calculator converts your height to inches, subtracts 60 to get the inches over 5 ft, then applies the three classic formulas: Devine (50 or 45.5 plus 2.3 per inch), Hamwi (48 or 45.5 plus 2.7 or 2.2 per inch), and Robinson (52 or 49 plus 1.9 or 1.7 per inch). You get all three results plus a healthy range at 90% to 110% of the Devine figure.
No single formula is universally the most accurate because each was derived from a different population. The Devine formula is the most cited in clinical practice because it was built for drug dosing. Robinson was fitted to observed population data and is often preferred in modern medical references as a general reference. Hamwi is the oldest, from 1964, built for dietitians and diabetes nutrition plans. The most honest answer is the range across the formulas rather than any one figure.
A woman 5 ft 5 in is 65 inches tall, which is 5 inches over 5 ft. Devine: 45.5 + 2.3 × 5 = 57.0 kg. Robinson: 49 + 1.7 × 5 = 57.5 kg. Hamwi: 45.5 + 2.2 × 5 = 56.5 kg. The healthy range, 90% to 110% of the Devine result, is about 51.3 to 62.7 kg. Frame size, muscle, and age shift where any individual sits inside that band.
Yes. The Devine formula is still the standard for calculating drug dosages and adjusted body weight in hospitals, and height and sex based predicted weight is used for ventilator settings. As a general health target, though, most doctors lean on BMI ranges, body composition, and clinical judgment rather than a single IBW number.
No. The formulas assume average body composition, so a muscular athlete, bodybuilder, or manual worker will exceed every formula while carrying very low body fat. For athletes, body fat percentage measured properly is a far better indicator of health than ideal weight or BMI.
The formulas themselves ignore age, but age still matters. Older adults may be healthiest slightly above the mid-range because some reserve helps with recovery from illness. The formulas do not apply to children at all: pediatric growth charts are used instead, and ideal body weight does not apply during pregnancy.
Ideal body weight gives a single number from your height and gender, usually near the centre of the healthy BMI range. BMI gives a range instead: the WHO healthy band of 18.5 to 24.9. Both are approximations and both share the same blind spot: neither can distinguish muscle from fat, and neither accounts for frame size, age, or health history.
No. Ideal weight formulas are population averages, not personal targets. They do not account for muscle mass, bone density, body composition, frame size, or fitness level. Treat the result as one reference point among many and discuss your actual healthy weight with a qualified healthcare professional. These are estimates, not medical advice.
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